The Grote Kerk was built between 1470–1498 by Anthonius Keldermans. It is dedicated to St Lawrence contains the tomb of Floris V, Count of Holland (d. 1296), a brass of 1546, and some paintings (1507). The mechanical clock has 27 bells by Melchior de Haze (1600s), and 8 modern bells. The tower bell was made by Jan Moer in 1525, with a diameter or 130 cm.
The two organs are world-famous. The smaller one, called the 'Koororgel', was built in 1511 by Jan van Covelens, and is built against the North wall of the church. It is the oldest playable organ in the Netherlands. The larger organ at the west end of the church is one of the most famous, significant and beautiful organs in the world. It was built by Jacobus Caltus van Hagerbeer, finished in 1645. The magnificent casework, which unusually stretches from floor to vault and makes the organ part of the architecture of the church, was designed by Jacob van Campen, a leading architect of the time. The enormous canvas shutters were painted by Caesar van Everdingen.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.